Transfer of My Grandfathers property to my aunt's name only and not to my father .

My Grandfather had two sons and four daughters . The 3rd daughter was divorced after marriage for some reason and was close to my grandfather . She returned to home and asked my grandfather to transfer a part of land to her name . Grandfather thought that she will be alone after as she is divorced and gave a part of the total land to her name at that time . My father's Elder brother demanded his part of land and got one too . After that my father went into some money problems and my the part of land that was in my aunt's name was sold by my grandfather only to solve the family problem . After that my Aunt demanded the remaining part which was in the name of grandfather name to her name , but all the other brother and Sisters were unaware of that fact . As she was very close to my grandfather , she took the advantage that my grandfather was ill at that time and convinced him to transfer the remaining total land to her name and surprisingly it happened . Now after many years we came to know this thing and now my aunt is saying to my father that the land is in my name and you just get out of here . The remaining daughters are in my father's support that my father also should get this property . Now the situation is we all are forced to file a case . The property was owned by my grandfather , and not ancestral . Is there anything we can do ? Btw we don't know if the property was given to her name was as a gift or not !! As she is refusing to Give any documents to prove it . Just refusing to share the land with my father , and saying is to leave ... Please answer this 🙏 This a chaos situation for my family !!